Thermal Reaction and Phase Evolution of APP/Al(OH)3/α-SiO2
The thermal reaction and phase evolution of APP/Al (OH)3/α-SiO2 with different mass ratios during heating were studied by TG, FTIR, XRD and SEM, respectively. When the temperature is not higher than 300 oC, mass ratio of mAPP:mAl (OH)3:mSiO2 has no effect on the phase evolution of APP/Al (OH)3/α-SiO2 and the main interaction product is AlNH4HP3O10. APP/Al (OH)3/α-SiO2 with lower content of APP, appears larger weight loss rate due to the thermal decomposition of Al (OH)3. The thermal reaction of APP/Al (OH)3/α-SiO2 is significantly influenced by the APP content as temperature rises to higher than 300 oC. The decomposition products of APP can chemically interact with Al (OH)3 to generate Al2P6O18 and Al (PO3)3 during 600 oC ~900 °C. When the content of APP increases, much more APP can chemically react with Al (OH)3 and also with part of α-SiO2 to generate SiP2O7. SEM shows the relatively dense microstructure due to micro-bridges of liquid phase with phosphate content increasing.